Hot water only when central heating on as well

[new1]

- Glow Worm Hideway 100 boiler (18 years old)

- CH system fitted with Grundfos Selectric Mk II pump

Problem: Until a few weeks ago we could get hot water by having only the hot water switch on. However, some of the radiators were also getting very hot.

Now we can only get hot water by switching on the CH as well.

I have checked the flow of water through the system. With only HW on, the flow goes one way. With CH on, the flow is reversed and I guess the HW is making it to the tank thanks to the pump pushing it round the opposite way.

Without the CH / pump on the hot water should be going straight from the bolier (in the kitchen) to the tank which is located above in the bathroom.

With only HW on, the pipes to the bathroom are only hot for around 1 metre and the return pipe is significantly cooler. The two central heating pipes are red hot.

Obviously, now is not the ideal time to have the CH on just to generate hot water.

Any help or ideas would be greatly appreciated.

Thanks in advance.

 

[Agile]

You seem to be describing a gravity hot water system.

You need to check the header tank has water in it.

If so then it would seem to indicate the gravity pipes have become mostly blocked with sludge.

You might be able to treat that with chemicals but power flushing or disassembly may be needed.

Tony

 

[new1]

Tony,

Yes, it is a gravity system.

We had the system flushed and treated in November last year. Would you expect the system to get blocked with sludge again so quickly?

NB I asked for the system to flushed and treated when we had TRVs fitted.

 

[Agile]

You say you had the "system flushed".

You seem to think that whatever that covered will have done a proper job. Now was that a POWER flush? What were the chemicals used?

Unfortunately, the fellow probably put a cheap chemical in the system and left it a few days and you immagined that doing that would completely clean the system.

Since he must have given a guarantee on his work, why dont you call him back at no additional charge to clean it out!

We charge about £400 to power flush but we would give a guarantee! How much did he charge? What guarantee do you think you have?

If he is a member of the Institute they have a complaints procedure!

Tony

 

[Nige F]

- Glow Worm Hideway 100 boiler (18 years old)

- CH system fitted with Grundfos Selectric Mk II pump

Problem: Until a few weeks ago we could get hot water by having only the hot water switch on. However, some of the radiators were also getting very hot.

the flow of water through the system. With only HW on, the flow goes one way. With CH on, the flow is reversed

Obviously, now is not the ideal time to have the CH on just to generate hot water.

Any help or ideas would be greatly appreciated.

Thanks in advance.

Even 4 a gravity/pumped setup..that`s wierd any chance of pics...I can`t figure WHY the "simplest" systems cause so much grief.......they must be simple I understand them(gravity/thermosyphon) and installed loads in the early 70`s